The present invention relates to data networking, telecommunication networking, and, in one embodiment, to systems and methods for enhancing Fibre-Channel links.
The Fibre-Channel standard defines a bi-directional link protocol, used to connect computers to disk drives and other peripherals. A typical Fibre-Channel link may have a bandwidth of 1063 Mbps and a span of up to 10 kilometers.
One typical application of Fibre-Channel is interconnecting computer CPUs with arrays of disk drive in large scale computing centers, as would be used in, e.g., financial transaction processing. For reasons of fault tolerance, it is desirable to locate redundant storage resources at remote locations. The advent of high data rate metropolitan optical networks including such networks based on the use of dense wave division multiplexing (DWDM) and/or SONET/SDH transport systems makes it possible to extend so-called storage area networks (SANs) that carry multiple Fibre-Channel links over distances much longer than 10 kilometers.
It is useful to apply the widely prevalent Fibre-Channel standard to communicate across DWDM networks and therefore minimize the need to redesign computing center equipment. Such DWDM networks can themselves employ protocol such as Gigabit Ethernet, 10 Gigabit Ethernet, SONET, etc. A transport interface is then used to interface the Fibre-Channel port to the transport network.
The transport interface encapsulates transmitted Fibre-Channel frames within transport layer frames or packets and also deencapsulates received Fibre-Channel frames from the transport layer frames or packets.
As explained in the co-filed U.S. patent application Ser. No. 10/403,396, now U.S. Pat. No. 7,145,877, entitled “APPARATUS AND METHOD FOR DISTANCE EXTENSION OF FIBRE-CHANNEL OVER TRANSPORT,” and in “INTELLIGENT FLOW CONTROL MANAGEMENT TO EXTEND FIBRE-CHANNEL LINK FULL PERFORMANCE RANGE” the flow control scheme incorporated within the Fibre-Channel standard does not cope well with links that extend much further than 10 km because of the delays inherent in receiving an indication of readiness for further transmissions from a distant port. As explained therein, the transport interface may incorporate a supplemental buffer in conjunction with other enhancements to extend the operating distance of a Fibre-Channel link while assuring that the ports do not overflow their internal receive buffers.
It is also desirable to combine multiple Fibre-Channel links onto the same transport layer link. A technique for accomplishing this is presented in U.S. patent application Ser. No. 10/366,867, entitled “FIBRE-CHANNEL OVER-SUBSCRIPTION OVER DWDM/SONET/SDH TRANSPORT SYSTEMS.” By use of the techniques described therein, one may combine multiple Fibre-Channel links onto a single transport link even where the transport link capacity is oversubscribed, i.e., the combined peak Fibre-Channel bandwidths exceed transport link capacity.
There are various types of Fibre-Channel ports. For example, N_Ports are used by individual Fibre-Channel nodes to communicate with one another and with Fibre-Channel switches. A Fibre-Channel switch port may operate as either an F_Port when communicating with a Fibre-Channel node or as an E_Port when communicating with another Fibre-Channel switch. To support the flow control and oversubscription features mentioned above, the transport interface needs to know the port type on each end of the link. This can of course be preprogrammed but it would be desirable for the transport interface to automatically detect the port types so that they need not be programmed in advance-by an operator.